Limitations in the Use of Small-Length Flexural Pivot in a Pseudo-Rigid-Body Model


This paper investigates the effective use of the pseudo-rigidbody model (PRBM) of a small-length flexural pivot (SLFP), examining its very definition, and providing helpful guidelines in the context of a compound compliant beam composed of both compliant and rigid segments. Traditionally, for convenience in modeling, the pseudo-rigid-body model of the small-length flexural pivot assumes the characteristic pivot to be placed at the center of the SLFP. It is also suggested that the length of the adjacent rigid segment is ten or more times larger than the length of the compliant segment. In recent times, a growing interest has been expressed to test this assumption and learn more about its limitations. This paper investigates the performance of the PRBM of the SLFP, for initially straight and initially curved compound compliant beams by varying the compliant to rigid segment length ratio. The error, defined by comparing the PRBM deflections with those obtained from the closed-form elliptic integral method, may be assigned an acceptable value in determining the limit value of the segment length ratio. Plots of the maximum deflection that may be obtained within an error limit of 3%, for various segment length ratios of a fixed-free, compound compliant beam are provided.

Meeting Name

ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, IDETC/CIE 2015 (2015: Aug. 2-5, Boston, MA)


Mechanical and Aerospace Engineering

Keywords and Phrases

Design; Compliant beams; Elliptic integrals; Error limits; Limit values; Maximum deflection; Pseudo rigid bodies; Pseudo-rigid body models; Segment lengths; Rigid structures

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


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© 2015 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

01 Aug 2015